Don't we need animals for farming (manure, grazing marginal land)?

The objection

“Farming needs animals. Manure keeps soil fertile, and grazing is the only way to get food from marginal land that crops can’t use.”

The answer

This is a real agronomic question, and it has a real answer.

On fertility: animals only recycle nutrients, they don’t create them, and mostly they recycle nutrients from crops we grew and fed to them. A cow sits in the middle of the loop rather than at the start of it. Stockfree (“veganic”) farming closes that loop without her, using green manures, cover crops, legume nitrogen-fixation, composted plant matter and rotation. The nitrogen a clover ley pulls from the air does not require a cow standing in the middle of the field, and working farms already run this way at commercial scale.

On marginal land: yes, some land can only be grazed. But the fact that we can graze it tells us nothing about whether we should. Grazing marginal land is spectacularly inefficient, a thin trickle of food from a vast area, which is why grass-fed beef carries among the highest land footprints of any food on Earth (Poore & Nemecek 2018). Follow the marginal-land argument honestly and it points the other way: land that grows almost no food but could grow forest, peat and carbon is worth more to us rewilded than carrying a few cattle. The strongest case for most of that hillside is to leave it wild.

Notice the sleight of hand in the objection. It inflates “animals are one historical method” into “animals are indispensable.” They are neither. We have fertility without them, and the land they “use up” is mostly land we’d be better off giving back.

If a hillside can feed a handful of people as pasture or store carbon and wildlife as forest, which use actually needs defending?